The purpose of war is to break the enemy’s will and impose the will of the victorious nation on the opponent. Occupying the enemy’s country and removing from authority its government to seize control of the foe’s sources of wealth and power has always been an effective method to realize this.

But this is not an easy feat. The adversary is almost surely going to oppose such adventure through the force of arms.

The aggressor needs to apply force over the target country to attain its purpose.

If diplomatic, economic and/or domestic incited strife are not sufficient or are deemed too lengthy to achieve the expected result, military force needs to be utilized.

But how should this force be applied for maximum effect?

World War One showed that the classical approach of defeating the adversary’s armed forces by using ground armies was still a practical way of doing business but at an appalling cost in blood and treasure.

Giulio Douhet, an Italian general and air power theorist, proposed a radically different approach of force application. His theory propounded the unrestricted bombing of enemy cities by air armies with the intention of killing and maiming civilians and leaving them homeless. Under such tremendous pressure, Douhet insisted, the civilians would find it impossible to bear the stress and they would direct their anger towards their government forcing it to capitulate.

This doctrine of aerial attack on civilians to kill and terrorize them was (rather unsuitably) christened “strategic bombing”.

Do-17 twin-engine Luftwaffe bombers in formation

Giulio Douhet, proponent of Strategic Bombing as the main mission of the air forces

The British RAF and American USAAF became the strongest tangible advocates (if not necessarily willingly supporters) of this theory during WW2.

The RAF leaned towards this doctrine with unbending focus. The British harnessed immense technological, economic, and military resources to make it succeed.

While they killed many civilians, and caused immense destruction on German cities, the RAF failed to force their adversary to surrender by an ample margin. Despite this failure, they became convinced that their approach was correct.

The American USAAF also advocated bombing civilians, but their approached differed markedly from the RAF and Douhet’s. Instead of unrestricted attacks against the German communities as a whole, to “break their morale”, the American centered their bombing efforts on industrial targets where civilians produced the means for sustaining their country’s war effort, like factories and oil refineries. It should be noted that for the Americans, children, women, and old people were not an intended target but collateral damage.

The British quickly learned that their bombers were not able to survive in the heavily defended skies over Germany so they carried out their bombing by night. The American approach, requiring daylight attacks to identify the targets, proved more effective, forcing the Germans to devote more resources to defend against this threat. However, both methods took a long time to start showing results : it was until mid-1943 that the RAF and the USAAF succeeded in seriously damaging some important German targets. However, the round-the-clock bombing could not prevent the German munition industry from achieving a huge expansion.

It would take the Americans another year (until Q2-Q3 1944) to badly hurt the German war machine with the partial destruction of their oil refineries (see next table). By that time the Soviets had been on the strategic offensive for a year already and had evicted the Wehrmacht from their country, soundly defeating the German army. Americans and British bombing campaigns bent the Reich but they did not break it.

Despite these facts, western literature ruled the “strategic bombing” doctrine, as superior to the use of the air force in support of the army. But was this the case?

The German Luftwaffe operational doctrine, established in Air Field Manual 16 published under the aegis of the Chief of Staff, General Walter Wever, placed the mission of the air force on the application of force on the enemy’s military forces in support of the army (and navy, when necessary). Only when certain conditions were present (i.e. stalemate) would the priority change to attack enemy’s industrial centers.

This mission has been defined as “tactical” by the Americans and British air theorist, implying that it was an inferior approach to win the war. Most historians have jumped to the same wagon it appears.

Effect of Strategic Bombing on German Industry.
Bars indicate total bomb tonnage delivered per year by both the RAF and the USAAF. Lines represent aircraft, AFV’s and guns manufactured in Germany every year. Munitions production in Germany increased dramatically despite the massive bombing.

Nonetheless, the historical record shows that the Luftwaffe was more successful than their enemies in breaking the enemy’s will.

By using strategic air forces, the British and Americans, after long hard-fought campaigns, only achieved tactical outcomes: they forced the Germans to find ways to defend themselves allocating resources better employed elsewhere.

By using a tactical air force, the Germans achieved strategic results in battles lasting a few weeks: they forced the complete defeat of Poland, Norway, Yugoslavia, Greece, Belgium, the Netherlands, and the biggest prize of all, France.

Why this difference?

German supply of Oil during WW2. The picture depicts the famous bombing of Ploesti by the USAAF in August 1943. Note that despite the bombing, 1943 was the best year for Germany. It was only after the second and specially the third quarters of 1944 that strategic bombing markedly affected German supply. By then, the Soviets had defeated the Germans for all practical purposes.

While in theory the bombing of manufacturing plants reduced output, in practice Germany, Great Britain and the United States found out that this was a very complex problem. It required precise intelligence to establish location of the industrial centers, their output, relative importance, construction materials and layout of the factories. Then it necessitated adequate weather to allow visual bombing, a distance to target within the range of the bombers, remarkable bombing accuracy with suitable bombs, sufficient bombload on targets to destroy them and the ability for most of the bombers to get back to base in one piece.

And even if the bombers hit the factories hard, stocks cushioned the impact in the short term and the factory could be repaired and dispersed to other locations relatively quickly.

Any part of this chain of events that did not occur favorably for the attacker, meant inferior results.

Factual results speak for themselves, only at the very end, did the German industrial sector shrink.

In contrast the Luftwaffe saw that the defeat of the enemy army means complete victory and to degrade the enemy’s army capability the important thing was that its troops did not receive supplies. This could be accomplished not only by destroying the factories, but by preventing the provisions from reaching the troops.

RAF's Short-Sgtirling four-engine strategic night bomber

The latter was possible by interdicting railroad and road communications: bombing supply trains and road convoys on the march and/or bridges, tunnels, cities and other infrastructure that caused the columns to stop. These attack methods prevented the transportation of supplies and the delivery of reinforcements to the engaged armies.

The impact was swift, because these supplies were needed at that time, and the lack of them caused the enemy’s armies to become notoriously brittle. Without food, oil, ammo, and replacements it was impossible to continue the fight.

An additional advantage of tactical bombing is that it required less intelligence resources to select key targets. Supply routes are very visible from the air, whereas camouflaged factories deep in enemy territory along with the plethora of other variables necessary for successful attack required more profound knowledge.

Finally, by facilitating the task of the army, ground troops could advance and capture the enemy factories for good, eliminating them from the equation altogether.

It was only when the German leaders committed the Luftwaffe to a multi-front war, that this legendary air force was pushed beyond its capacity, because its force structure was insufficient. When Germany invaded the Soviet Union, the Luftwaffe was simultaneously fighting wars in the west, defending the continent and in the extensive Mediterranean Theater. The Luftwaffe head of Operations, General Otto Hoffmann von Waldau recognized this strategic mistake immediately and warned the Luftwaffe Chief of Staff Hans Jeschonnek to no vail.

Had the Luftwaffe been designed as a strategic air force from the beginning, the swift strategic victories over its opponents would have been beyond its grasp. Lack of a striking bombing force capable of interdicting enemy rear areas signified that a vital component of the Blitzkrieg would be missing, seriously endangering the advance of the armored spearheads. The deep penetrations would not have been successful.

Historic facts show that the Heer was not able to attain any major offensive victory during WW2 without Luftwaffe-obtained air superiority.

Without the capability to project this air superiority Germany would have faced a long-protracted war with her western enemies, preventing any invasion of the Soviet Union.

The alternative, often mentioned by some historians, of Germany developing both a tactical and a strategic air force was simply impossible (see the next chart) as Germany did not have the resources to develop force structures of the required sized simultaneously .

Graph illustrating the effect on the Luftwaffe tactical strike force by developing a strategic bomber force of different sizes.
Resources were not infinite. Any addition to the strategic bomber force was possible only by a corresponding reduction on the size of the tactical bomber force because of several critical shortages.
The chart shows that a Strategic force of 100 four-engine bombers would have reduced the tactical strike force by 12%. This reduction was not very detrimental to the Blitzkrieg and it is likely that the smashing victories would still have been attained by the German arms. Nevertheless, this small heavy bomber force would have been completely ineffectual, representing only 4% of the size of the USAAF heavy bomber force in January of 1944 when the US was finally able to deliver consistent heavy blows. The chart shows that by the time the Luftwaffe heavy bomber force reached 400 four-engine bombers, the tactical strike force would have been half the size it attained historically in June 1941. This reduction would have made the Blitzkrieg victories practically impossible, with no corresponding gain. A 400 heavy bomber force (15% of the size of the USAAF heavy bomber force in Jan ‘44) would have been useful only for occasional telling blows to the Soviet industry, but it would have been fully insufficient to paralyze it.